There are many urinary tract conditions that are treated by delivering to the urinary bladder drugs or other substances, such as radioactive substances, and antibiotics. Such conditions include urinary incontinence, urinary tract infections, bladder tumors, and bladder dysfunctions. In order to obtain controlled release of a substance in the urinary bladder it is known to insert a device into the bladder that stores the substances and releases them slowly over time. WO 2004/041124 discloses a device comprising a balloon that is inflated inside the urinary bladder. The device also comprises an insert that is affixed to the balloon and that stores and releases substances into the bladder.